Publications by authors named "Colton Linnertz"

Coronaviruses have caused three severe epidemics since the start of the 21 century: SARS, MERS and COVID-19. The severity of the ongoing COVID-19 pandemic and increasing likelihood of future coronavirus outbreaks motivates greater understanding of factors leading to severe coronavirus disease. We screened ten strains from the Collaborative Cross mouse genetic reference panel and identified strains CC006/TauUnc (CC006) and CC044/Unc (CC044) as coronavirus-susceptible and resistant, respectively, as indicated by variable weight loss and lung congestion scores four days post-infection.

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Whole virus-based inactivated SARS-CoV-2 vaccines adjuvanted with aluminum hydroxide have been critical to the COVID-19 pandemic response. Although these vaccines are protective against homologous coronavirus infection, the emergence of novel variants and the presence of large zoonotic reservoirs harboring novel heterologous coronaviruses provide significant opportunities for vaccine breakthrough, which raises the risk of adverse outcomes like vaccine-associated enhanced respiratory disease. Here, we use a female mouse model of coronavirus disease to evaluate inactivated vaccine performance against either homologous challenge with SARS-CoV-2 or heterologous challenge with a bat-derived coronavirus that represents a potential emerging disease threat.

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RNA viruses quickly evolve subtle genotypic changes that can have major impacts on viral fitness and host range, with potential consequences for human health. It is therefore important to understand the evolutionary fitness of novel viral variants relative to well-studied genotypes of epidemic viruses. Competition assays are an effective and rigorous system with which to assess the relative fitness of viral genotypes.

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Background: The development of peanut allergy is due to a combination of genetic and environmental factors, although specific genes have proven difficult to identify. Previously, we reported that peanut-sensitized Collaborative Cross strain CC027/GeniUnc (CC027) mice develop anaphylaxis upon oral challenge to peanut, in contrast to C3H/HeJ (C3H) mice.

Objective: This study aimed to determine the genetic basis of orally induced anaphylaxis to peanut in CC027 mice.

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Article Synopsis
  • Coronavirus can lead to serious health issues, exemplified by SARS-CoV, MERS-CoV, and SARS-CoV-2 outbreaks, indicating significant variation in disease outcomes among infected individuals.
  • Researchers are using mouse models and human genetic studies to identify gene locations that influence how these coronaviruses affect infection severity and replication.
  • Their findings highlight specific genes that may play roles in virus response, offering insights for future research on how to combat similar viruses that jump from animals to humans.
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Inactivated whole virus SARS-CoV-2 vaccines adjuvanted with aluminum hydroxide (Alum) are among the most widely used COVID-19 vaccines globally and have been critical to the COVID-19 pandemic response. Although these vaccines are protective against homologous virus infection in healthy recipients, the emergence of novel SARS-CoV-2 variants and the presence of large zoonotic reservoirs provide significant opportunities for vaccine breakthrough, which raises the risk of adverse outcomes including vaccine-associated enhanced respiratory disease (VAERD). To evaluate this possibility, we tested the performance of an inactivated SARS-CoV-2 vaccine (iCoV2) in combination with Alum against either homologous or heterologous coronavirus challenge in a mouse model of coronavirus-induced pulmonary disease.

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Background: The development of peanut allergy is due to a combination of genetic and environmental factors, although specific genes have proven difficult to identify. Previously, we reported that peanut-sensitized CC027/GeniUnc (CC027) mice develop anaphylaxis upon oral challenge to peanut, unlike C3H/HeJ (C3H) mice.

Objective: To determine the genetic basis of orally-induced anaphylaxis to peanut in CC027 mice.

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Article Synopsis
  • Human genetic variation may influence the outcomes of hepatitis C virus (HCV) infection, but suitable experimental models are limited.
  • The Collaborative Cross (CC) mouse strains were infected with Norway rat hepacivirus, revealing different outcomes: some strains cleared the virus, while others experienced chronic infection for over 10 months, showing varied immune responses and liver damage.
  • This study highlights the importance of host genetics in viral infections and offers insights into the mechanisms behind virus clearance, chronic disease development, and potential therapeutic strategies.
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Variation in immune homeostasis, the state in which the immune system is maintained in the absence of stimulation, is highly variable across populations. This variation is attributed to both genetic and environmental factors. However, the identity and function of specific regulators have been difficult to identify in humans.

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Understanding the pharmacogenomics of opioid metabolism and behavior is vital to therapeutic success, as mutations can dramatically alter therapeutic efficacy and addiction liability. We found robust, sex-dependent BALB/c substrain differences in oxycodone behaviors and whole brain concentration of oxycodone metabolites. BALB/cJ females showed robust state-dependent oxycodone reward learning as measured via conditioned place preference when compared with the closely related BALB/cByJ substrain.

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Article Synopsis
  • * Researchers used a genetically diverse group of mice, known as the Collaborative Cross (CC), along with a library of bacterial mutants, to explore the relationship between bacterial genetics and host immunity.
  • * Findings indicated that different mouse strains showed significant differences in their susceptibility to infection and immune responses, highlighting specific host-pathogen interactions that affect disease outcomes.
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Thermal nociception involves the transmission of temperature-related noxious information from the periphery to the CNS and is a heritable trait that could predict transition to persistent pain. Rodent forward genetics complement human studies by controlling genetic complexity and environmental factors, analysis of end point tissue, and validation of variants on appropriate genetic backgrounds. Reduced complexity crosses between nearly identical inbred substrains with robust trait differences can greatly facilitate unbiased discovery of novel genes and variants.

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Article Synopsis
  • The laboratory mouse is the leading model in biomedical research due to its well-studied genome, but genetic quality control (QC) in mouse studies lacks standardization and cost-effective methods.* -
  • The MiniMUGA is a new genetic QC platform featuring over 11,000 probes that offers advantages like chromosomal sex determination, substrain discrimination, and easy-to-read reports on genetic data.* -
  • Testing MiniMUGA on nearly 7,000 samples showed it performs well, matching or exceeding earlier versions in accuracy, and it also provides new consensus genotypes for multiple inbred mouse strains.*
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Two key features of recombinant inbred panels are well-characterized genomes and reproducibility. Here we report on the sequenced genomes of six additional Collaborative Cross (CC) strains and on inbreeding progress of 72 CC strains. We have previously reported on the sequences of 69 CC strains that were publicly available, bringing the total of CC strains with whole genome sequence up to 75.

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Introduction: We recently showed that tagging single-nucleotide polymorphisms across the SNCA locus were significantly associated with increased risk for Lewy body (LB) pathology in Alzheimer's disease (AD) cases. However, the actual genetic variant(s) that underlie the observed associations remain elusive.

Methods: We used a bioinformatics algorithm to catalog structural variants in a region of SNCA intron 4, followed by phased sequencing.

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The molecular genetic basis that leads to Lewy Body (LB) pathology in 15-20% of Alzheimer disease cases (LBV/AD) was largely unknown. Alpha-synuclein (SNCA) and Leucine-rich repeat kinase2 (LRRK2) have been implicated in the pathogenesis of Parkinson's disease (PD), the prototype of LB spectrum disorders. We tested the association of SNCA variants with LB pathology in AD.

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Background: We investigated the genomic region spanning the Translocase of the Outer Mitochondrial Membrane 40-kD (TOMM40) and Apolipoprotein E (APOE) genes, that has been associated with the risk and age of onset of late-onset Alzheimer's disease (LOAD) to determine whether a highly polymorphic, intronic poly-T within this region (rs10524523; hereafter, 523) affects expression of the APOE and TOMM40 genes. Alleles of this locus are classified as S, short; L, long; and VL, very long based on the number of T residues.

Methods: We evaluated differences in APOE messenger RNA (mRNA) and TOMM40 mRNA levels as a function of the 523 genotype in two brain regions from APOE ε3/ε3 white autopsy-confirmed LOAD cases and normal controls.

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Hepatitis C virus (HCV) modulates host lipid metabolism as part of its lifecycle and is dependent upon VLDL for co-assembly and secretion. HCV dyslipidemia is associated with steatosis, insulin resistance, IL28B genotype and disease progression. Apolipoprotein E (ApoE) is an important lipid transport protein, a key constituent of VLDL, and is involved in immunomodulation.

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Introduction: A highly polymorphic T homopolymer was recently found to be associated with late-onset Alzheimer's disease risk and age of onset.

Objective: To explore the effects of the polymorphic polyT tract (rs10524523, referred as '523') on cognitive performance in cognitively healthy elderly individuals.

Methods: One hundred eighty-one participants were recruited from local independent-living retirement communities.

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We previously discovered that a polymorphic, deoxythymidine-homopolymer (poly-T, rs10524523) in intron 6 of the TOMM40 gene is associated with age-of-onset of Alzheimer's disease and with cognitive performance in elderly. Three allele groups were defined for rs10524523, hereafter '523', based on the number of 'T'-residues: 'Short' (S, T≤19), 'Long' (L, 20≤T≤29) and 'Very Long' (VL, T≥30). Homopolymers, particularly long homopolymers like '523', are difficult to genotype because 'slippage' occurs during PCR-amplification.

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SORL1 has been identified as a major contributor to late onset Alzheimer's disease (LOAD). We test whether genetic variability in the 5' of SORL1 gene modulates the risk to develop LOAD via regulation of SORL1-messenger ribonucleic acid (mRNA) expression and splicing. Two brain structures, differentially vulnerable to LOAD pathology, were examined in 144 brain samples from 92 neurologically normal individuals.

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Genetic variability at the 3' region of SNCA locus has been repeatedly associated with susceptibility to sporadic Parkinson's disease (PD). Accumulated evidence emphasizes the importance of SNCA dosage and expression levels in PD pathogenesis. However, the mechanism through which the 3' region of SNCA gene modulates the risk to develop sporadic PD remained elusive.

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Article Synopsis
  • Genetic variability in the SNCA gene has been linked to the risk of developing sporadic Parkinson's disease (PD), with evidence showing that SNCA gene expression affects PD pathology.
  • The study analyzed human brain samples from different areas affected by PD to see how certain genetic variants influenced SNCA-mRNA levels.
  • Findings revealed that the protective Rep1-259 bp allele reduced SNCA-mRNA levels significantly compared to risk-associated alleles, highlighting the importance of genetic regulation in PD development.
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Alpha-synuclein (SNCA) gene has been implicated in the development of rare forms of familial Parkinson disease (PD). Recently, it was shown that an increase in SNCA copy numbers leads to elevated levels of wild-type SNCA-mRNA and protein and is sufficient to cause early-onset, familial PD. A critical question concerning the molecular pathogenesis of PD is what contributory role, if any, is played by the SNCA gene in sporadic PD.

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